How do you replace a thermostat on an Audi 4.2 engine?

If you have to ask, you probably shouldn't be attempting it. It involves a lift, draining the coolant, removing the front bumper, putting the core support into the service position, removing the belts, moving the alternator, loosening the mounting plate that supports the fan clutch, Power Steering pump etc. - all so you can get to the thermostat housing! If you had a Jaguar, changing a thermostat would take less than fifteen minutes. Instead, the Germans made it a four hour job for a professional.